By Bob Walker
We have seen quite a few Red Crossbills (Loxia curvirostra) in Los Alamos County this winter and spring. These remarkably adapted birds give you the first impression of being “just another finch” until you notice their oddly-shaped bills, which cross at the tips. The brick-red males and pale yellow females are noticeably larger than House Finches, but otherwise resemble these more familiar feeder birds. To make things more confusing, their young resemble female House Finches even more, being overall brown birds with heavy streaking on the bellies. If you visit the Los Alamos Nature Center this month, stay around in the Wildlife Observation Room for a bit, and sooner or later, some Red Crossbills will almost certainly stop by to pick up some seed from the house-like feeder on the pole in front of the windows. We must be seeing a local family of Crossbills, because there are often a couple of juveniles accompanying their parents.
Why are their bills crossed? It’s an adaptation that allows them to extract seeds efficiently from pine cones, the primary staple of their diet.
Red Crossbills stay here all year long but do wander around in search of healthy crops of pine cones; we must have good food resources now, because we have been seeing them for some time, and they are raising young. Unlike most birds, Crossbills will breed almost any time of the year, so long as there is an adequate food supply. There is much discussion in the ornithological literature whether or not there is just one species of Red Crossbill, or if in fact there are many species of Crossbills, distinguishable primarily by their vocalizations, and by minor differences in the timing of their breeding.